class Person{
    @readonly gender = 'male'
}

function readonly(target, attrName, description){
    console.log('target:', target); // 类的 prototype 对象
    console.log('attrName:', attrName); // 类的成员属性名
    console.log('description:', description);// 类成员属性的装饰器对象

    description.writable = false
}

let Andy = new Person()
//Andy.gender = 'female'